1. Field of the Invention
The present invention relates to a heat transfer medium with a high heat transfer rate, a heat transfer surface, and a heat transfer element and device using the heat transfer medium.
2. Background of the Invention
Efficiently transporting heat from one location to another always has been a problem. Some applications, such as keeping a semiconductor chip cool, require rapid transfer and removal of heat, while other applications, such as dispersing heat from a furnace, require rapid transfer and retention of heat. Whether removing or retaining heat, the heat transfer abilities of the material utilized define the efficiency of the heat transfer.
For example, it is well known to utilize a heat pipe for heat transfer. The heat pipe operates on the principle of transferring heat through mass transfer of a fluid carrier contained therein and phase change of the carrier from the liquid state to the vapor state within a closed circuit pipe. Heat is absorbed at one end of the pipe by vaporization of the carrier and released at the other end by condensation of the carrier vapor. Although the heat pipe improves thermal transfer efficiency as compared to solid metal rods, the heat pipe requires the circulatory flow of the liquid/vapor carrier and is limited by the association temperatures of vaporization and condensation of the carrier. As a result, the heat pipe's axial heat conductive speed is further limited by the amount of latent heat of liquid vaporization and on the speed of circular transformation between liquid and vapor states. Further, the heat pipe is convectional in nature and suffers from thermal losses, thereby reducing the thermal efficiency. It is generally accepted that when two substances having different temperatures are brought together, the temperature of the warmer substance decreases and the temperature of the cooler substance increases. As the heat travels along a heat-transfer tube from a warm end to a cool end, available heat is lost due to the heat transfer capacity of the tube material, the process of warming the cooler portions of the tube and thermal losses to the atmosphere.
To overcome the intrinsic limit of the materials, the inventor discloses a composition and the method for preparation in U.S. Pat. No. 6,132,823, issued Oct. 17, 2000.
In that Patent, the heat transfer medium was made up of three layers deposited on a substrate. The first two layers were prepared from solutions that are exposed to the inner wall of the tube. The third layer was a powder comprising various combinations. The first layer was placed onto an inner tube surface, the second layer was then placed on top of the first layer to form a film over than inner conduit surface. The third layer was a powder preferably evenly distributed over the inner conduit surface.
The first layer was nominated an anti-corrosion layer to prevent etching of inner conduit surface. The second layer was said to prevent the production of elemental hydrogen and oxygen, thus restraining oxidation between oxygen atoms and the conduit material. The third layer is called the “black powder” layer. It is said that the layer can be activated once it is exposed to thermal activation point 38° C. Thus it is said that removing any of the three layers of the heat transfer medium in the previous patent will cause an adverse impact on heat transfer performance.
In addition, the method for preparing the prior medium was complicated and cumbersome. For instances, formation of the first layer may involve nine chemical compounds prepared in seven steps. Formation of the second layer may involve fourteen compounds prepared in thirteen steps. Formation of the third layer may involve twelve compounds prepared in twelve steps. In addition, if the components of each layer are combined in an order not consistent with the listed sequence and conforming to the exceptions noted in my patent, the solutions made for such preparation were potentially unstable.
Generally, the heat transfer medium used by the present invention eliminates or improves upon many of the noted shortcomings and disadvantages. The preferable heat transfer medium of this invention was made up of one layer deposited on a substrate while the most preferable one is one single layer. The layer was prepared from a group of twelve inorganic compounds selected from the list below and formed in a single layer. The improved medium not only reduces the number and types of compounds used in the medium, but also effectively reduces the number of steps required for the preparation of the medium without compromising heat transfer efficiency.